Cutting apparatus of the type generally described above is well known in the tube-making art as is exemplified by U.S. Pat. Nos. 3,938,415, 4,108,029 and 4,294,147 owned by the assignee of the present invention, the entire disclosures of which patents are hereby incorporated by reference herein. While the prior art machines disclosed in these patents are both highly efficient and are well suited for their intended purpose, certain aspects thereof are nevertheless subject to improvement.
The above-mentioned patents disclose tube cutting apparatus which, in principal part, comprises a die set which operates with, but is removable as a unit from, a press. The die set comprises reciprocally movable upper and lower platen assemblies, a set of two holder members, usually slides, mounted on the lower platen assembly, and two sets of stock-clamping jaws mounted by bolts on the holders. The jaws are configured to conform to and hold the stock when closed thereon, for the purpose of preventing movement between the stock and the die set components during the cut. The die set further comprises either one or two blades, each of which must pass between the jaw sets during movement of the platen assemblies. A mechanism is provided for closing and opening the jaws in timed relationship to the reciprocal movement of the platen assemblies and blades.
It is essential in this arrangement that the jaws be precisely located on the holders so that the stock is firmly held and the blades pass between the spaced-apart side faces of the jaws with just the right clearance. Proper location and alignment in prior art die sets is somewhat laboriously achieved during a "set-up" operation, using spacers and appropriate tools. Changing die sets, for example to accommodate stock of a different size, or to replace worn jaws, results in lost production time and, therefore, in preferably accomplished in the least possible time, but without losing the required accuracy.
The difficulty encountered in the set-up operation is due not only to the need for precise location, but also to the need to handle machine bolts which secure the jaws to the holders. These bolts have a way of becoming dirty, damaged and even lost, if only temporarily. the conscientious worker carefully handles these bolts, cleans them as necessary, and turns them to just the right degree of tension to hold the jaws in the proper location; all requiring time and "feel" which comes only from experience.